1. Technical Field
The present invention relates to a technical field of an exposing device including light-emitting element arrays having plural light-emitting elements and lens arrays having plural lenses that focus lights from the light-emitting elements. The present invention also relates to a technical field of an image forming apparatus of an electrophotographic system such as a copying machine, a facsimile, or a printer that includes the exposing device and uses a liquid developer.
2. Related Art
An exposing device including light-emitting element arrays having plural light-emitting elements two-dimensionally disposed, respectively, and lens arrays having plural lenses that focus lights from the light-emitting elements has been proposed (see, for example, JP-A-6-278314 and JP-A-2001-63139). In the exposing device disclosed in JP-A-6-278314, the light-emitting element arrays and the lens arrays are disposed in a first direction as a main scanning direction and a second direction as a scanning direction orthogonal to or substantially orthogonal to the first direction. A photosensitive member is exposed in spots of two rows by the lights from the light-emitting elements. In the exposing device disclosed in JP-A-2001-63139, lights from the light-emitting elements in plural rows is irradiated on a photosensitive member in a line shape to form a latent image. In that case, the lights from all the light-emitting elements are focused on the photosensitive member by one optical system lens.
When the lens arrays are used, it is possible to use light-emitting elements larger than those used in an exposing device in the past in which the lens arrays are not used. Therefore, advantages such as an increase in exposure intensity, the extension of durable life, and an increase in selections of light-emitting elements are realized by using the lens arrays.
On the other hand, when the lens arrays are used, it is difficult to focus the lights from the light-emitting elements on the photosensitive member. Therefore, when the exposing device including light-emitting element arrays and lens arrays two-dimensionally arrayed, respectively, is built in an imaging forming apparatus, the lights may be defocused. Therefore, exposing devices that satisfy predetermined criteria for focusing and pass a test decrease. As a result, the yield of exposing devices falls.
However, it is difficult to effectively solve this problem with the exposing devices disclosed in JP-A-6-278314 and JP-A-2001-63139.